x86/amd-iommu: Workaround for erratum 63
There is an erratum for IOMMU hardware which documents
undefined behavior when forwarding SMI requests from
peripherals and the DTE of that peripheral has a sysmgt
value of 01b. This problem caused weird IO_PAGE_FAULTS in my
case.
This patch implements the suggested workaround for that
erratum into the AMD IOMMU driver. The erratum is
documented with number 63.
Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c1b17e9..498c8c7 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -509,6 +509,26 @@
amd_iommu_dev_table[devid].data[i] |= (1 << _bit);
}
+static int get_dev_entry_bit(u16 devid, u8 bit)
+{
+ int i = (bit >> 5) & 0x07;
+ int _bit = bit & 0x1f;
+
+ return (amd_iommu_dev_table[devid].data[i] & (1 << _bit)) >> _bit;
+}
+
+
+void amd_iommu_apply_erratum_63(u16 devid)
+{
+ int sysmgt;
+
+ sysmgt = get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT1) |
+ (get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT2) << 1);
+
+ if (sysmgt == 0x01)
+ set_dev_entry_bit(devid, DEV_ENTRY_IW);
+}
+
/* Writes the specific IOMMU for a device into the rlookup table */
static void __init set_iommu_for_device(struct amd_iommu *iommu, u16 devid)
{
@@ -537,6 +557,8 @@
if (flags & ACPI_DEVFLAG_LINT1)
set_dev_entry_bit(devid, DEV_ENTRY_LINT1_PASS);
+ amd_iommu_apply_erratum_63(devid);
+
set_iommu_for_device(iommu, devid);
}